Continuity mistake: When the Lost Boys see that they have shot down Wendy, they turn around and say "Tootles has killed her" and they are spread out, but when Peter comes in a second later, they are grouped together. (00:34:15)
Continuity mistake: At the Black Castle, John, Michael and Tiger Lily are in the water, yet when they try to open the gate their clothing, especially John and Michael's gowns, are very obviously not as wet or as clingy as they should be. (00:48:40)
Continuity mistake: When Hook makes Wendy tell the story of Peter Pan and subsequently shoots Noodler, the first of the two pirates to go down at storytime, the camera cuts to the next shot and Hook's pistol is out of his hand, which is not only visible, but being held up in the air, as opposed to under his right arm where he shot from.
Continuity mistake: At the Black Castle, Princess Tiger Lily's make-up completely rubs off when she is in the water but when she kisses John, she has a dark area around her eyes. (00:45:55 - 00:48:50)
Continuity mistake: There is a shot of Nana sleeping in her house before we see Peter flying over Wendy, who is also asleep. Then there is another shot of Nana coming out of her house barking. The toys' positions near Nana's house differ in both shots and Nana did not move them. (00:06:05)
Continuity mistake: Peter kicks the jack-in-the-box and it falls over, but when Wendy starts to say, "But there's no such thing as," Peter flies toward her and the jack-in-the-box is upright now. (00:18:55)
Continuity mistake: When Wendy walks between John and Michael's beds, you can see John and Michael sleeping, but when Wendy asks Peter if John and Michael can come too, in the next shots of John and Michael, their sleeping positions have suddenly changed.
Answer: It's not that you never age, it's that you never grow up, i.e. pass into puberty and become an adult.
Myridon